When China did tell the world definitely about Covid-19 on January 7.
If all other countries had been prepared for a pandemic (which has happened in the past and was highly likely to repeat with increased international travel), prepared with supplies of PPE, medical wards, border airports & ports designed and equipped to commence health checking at very short notice.
and then shortly after January 7 closed borders and health checked and segregated all arrivals. In that scenario even allowing for arrivals not showing symptoms transmission would have died out and the crisis outside China would have been all over before the end of March.
We should not ignore that more than twice as many people arrived in Australia infected from USA than China. At least China warned us that had a problem. USA had a huge infection problem and did not tell us for what appears to be 6 weeks. That failure on the part of USA for more than a month was far more significant in regard to infection rates in Australia than the delay of 2 or 3 weeks from China at the very beginning, because transmission was much wider later on when USA was not telling us.
The Key reason why our economy is shutdown is because we were not prepared for a pandemic and we should have been, and we are still shutdown even though community transmission is almost non existent because we will not be properly prepared for a pandemic for at least another month. It will have taken us 4 to 5 months after January 7 to get to the level of pandemic preparation we should have been at in December 2019.
We cannot blame China that we ignored the need to be properly prepared for a pandemic that was likely to happen sometime.
If we can justifiably point the finger at China for being tardy at the very beginning and warning the world there is a much bigger question to ask the USA for its much longer delay which is where the overall majority of our infections have come from.
I am particularly pissed because I was in the USA from Jan through to early March. I was clearly being potentially exposed I realise now in hindsight, but there was no attention to the issue while I was there. In the USA all attention was on the election. I was shocked to arrive back in Australia and find people social distancing.